New engine showed up, XTM24.7

[olds97_lss]

YAY!!!!!

I was afraid it would show up next week as it's supposed to be relatively nice here Saturday and Sunday hovering around 60F and sunny. Perfect break-in weather. If all goes well, I'll get it broken in Saturday.

This replaced a STS D30 that I couldn't get tuned right or running right. I had one of these engines and it had decent power and held a tune pretty well. Considering my savage has a 3-speed, the non-over-the-top engine should do pretty good for low end and top speed.

I have hot bodies extended tvp's with their rear dog bone. The little shaft is loose and works it's way out of the end of the dog bone. Anyone have a quick fix for this?

Anyway, photo's of it installed and on my workbench:

I could have swore the head on the 24.7 I had before wasn't a smooth top head... wonder why it changed. Crap, they did change it. They also changed the banjo fitting on the carb to plastic from brass... I hope they didn't change much else with this engine!

The old head from my last XTM in my buggy that I traded for the savage:

 

[jon2]

Ahh the good ole days. reminds me of my old one..

 

[Scrogg]

Your dogbone issue, maybe a little JB Weld? Throw a big piece of shrink wrap over the bone and melt it in place over the cup. Might work for a while.

 

[HeartBreak]

Actually, I'd put a little fuel tubing inside of the drive cup to act as a spacer. That should help "center" the dogbone up a little bit.

edit; re-read the dogbone part... Perhaps a little JB weld might help. Otherwise, you might want to contact Hotbodies.. They might warranty the part.

 

[olds97_lss]

Actually, I'd put a little fuel tubing inside of the drive cup to act as a spacer. That should help "center" the dogbone up a little bit.

edit; re-read the dogbone part... Perhaps a little JB weld might help. Otherwise, you might want to contact Hotbodies.. They might warranty the part.

I did contact them and I can order one, $8, so not a big deal. Just takes time to get it here and to tear the rear off the rig to replace it. I'll probably just order a couple and try to be easy on my break-in tomorrow. I may try and make something I can lock onto the outside of the cup just to keep the pin from working out tonight. It will be hack, but I's GOTS TO RUN!!!

 

[olds97_lss]

Well... I broke it in today... got probably about 800-900 cc's through it. Really came to life around tank 5 once I leaned it out a bit. I'm thinking a more restrictive pipe than the HPI polished might help even out the tune a bit. Or a bit more run time. Not sure which. May try to scavenge another losi HT pipe like I have on my LRP that I like a lot. Much more quiet, but a better power band.

16/49 + 3 speed + XTM24.7 = wheelies

If I had grippier tires on it, it would have wheelied much easier. But I'm running traxxas chevrons and it was 50F out today and the grass was damp. Whenever I hit a dry spot of lawn, wheelies were to be had. The tires would just spin on the concrete in the skate park, but acceleration was really great.

Unfortunately, somewhere around tank 7, I scarred the new engine:

Somewhere around tank 8-9'ish, I busted 2 teeth of the spur gear (can see it in the photo if you look close), which ended my day. All in all, a great day for me. A little cool, a little windy, but it was a good 2.5-3 hours of break-in/running time.

I obviously need to start working on a roll bar... C'MON HALF BODY!!!

Unfortunately, I don't have another 49T spur. So, I may throw in a 52T to run it a bit more tomorrow, but I'm afraid it won't shift out of first with that low of gearing. I'll have to take my jato with just to drive something. Or, I'll stop at lowes and pickup some roundbar for a new roll bar... decisions, decisions...

 

[HeartBreak]

Ya know, me amigo, I think you might have made me look twice at the XTM. The ones I had were the old style (seen in the buggy picture above), and it was a nightmare to keep from overheating (head was probably too small)...

I think yours might be the XTM 457, which I am looking at... It's a .28 engine, which falls right in line at my minimum specs.

That's a bummer about the head and spur, but those seem to be the Savages' favorite casualties. Might I suggest the Savage X rollbar set? It's cheap, and helps prevent head damage (or crankcase damage - I've killed a motor or two that way).

edit; just noticed the extended chassis.... I don't think the X rollcage would fit.

 

[olds97_lss]

I think yours might be the XTM 457, which I am looking at... It's a .28 engine, which falls right in line at my minimum specs.

I don't think it is... I mean, I got it on ebay for $89 BIN. It said all over that it was a 24.7. Mine didn't say 24.7 on it like the one on hobby people, but it's shaped the same:

The 457 has a different shape to it:

The 457 also has a black crank case and carb.

I think XTM just changed the 24.7 a bit. It is an old engine model. They just updated it a bit.

With the 457 listed new at $169... I'd just by the LRP28S3 on tower with the $20 coupon which would put it at $149. With tax, it would be around $169 anyway since tower is in IL.

 

[Lessen]

Fortunately, you take damage lightly. That's good. If I broke my head like that after 7 tanks I would be thoroughly disgusted with myself and certainly wouldn't refer to it as a good day. Glad to hear your having fun with an engine that's actually tuneable.

 

[olds97_lss]

Fortunately, you take damage lightly. That's good. If I broke my head like that after 7 tanks I would be thoroughly disgusted with myself and certainly wouldn't refer to it as a good day.

Well... considering I wasted 3/4 of a gallon of fuel, got repeated blisters and busted up knuckles trying to get the STS working... a chipped fin still was a better day than all the days I've had so far.

I was disappointed, but accidents happen. Not much I can do about it now. I may take the dremel to it and remove the entire fin just so it doesn't look so bad.

 

[olds97_lss]

Just in case anyone is keeping track and so I can keep track of what works for me.

I'm now running:

Spur/CB: 47/16
Clutch: HPI Teflon 3-shoe
Trans: 3 speed
Engine: XTM 24.7
Fuel: 25% byrons
Plug: mccoy MC-8
Pipe: Duratrax Warhead stock pipe, HPI header
Tires: traxxas chevrons
Avg run temp: 240F
Ambient: 64F

I was running whatever plug comes in the engine when new for break-in yesterday. I replaced it with a mccoy mc-8 today and it really evened it out and dropped the temps some. Power was more instant as well.

I'm running a duratrax warhead pipe. Pretty quiet and seems to work really well with the XTM.

I was running an HPI polished savage pipe, but I couldn't seem to get a tune that I liked. Muddy in the middle and if I leaned enough to clear that up, it was too lean on top and bottom. Very odd. Then I tried an integy (I think it's integy) pipe I had laying around with a slightly different shape, but equally large exhaust stinger. It ran about the same as the HPI, but the window of muddiness was narrower. I then tried the warhead pipe. A lot quieter and not as aggressive power output on the low RPM range, but now it runs clean and cool from idle to WOT.

I wasn't pulling wheelies, but I also wasn't trying for the first few tanks. I had just installed the new pipe and changed the plug, so I was just tuning it in a big parking lot. Then when I felt good with the tune, I went into the lawn and punched the gas a few times only to hear the dreaded grinding of diff gears... so I was easy on it for 3 tanks just to have some fun. I forgot how well a savage flies. Before I was trying "wheelies", I would just roll on the throttle quick and power was really good. It's pulling the 47/16 gearing really well and I think I'll keep it that way. I may drop down to a 49 for winter since I run a bit larger tire, but I was surprised. It gets up and goes just as quick as the stupid STS I had. Except this runs better and has better top end.

I must have gotten a bad STS... or a really good XTM. Either way, I'm happy now and I just need to hit ebay for a new rear diff.